Viral transformation results in changes in an array of surface related phenomena such as: (1) loss of density-dependent inhibition of growth; (2) increase in cell agglutinability by a variety of plant lectins; (3) reduction in substrate and cell-to-cell adhesiveness which may be related to the in vivo metastatic properties of tumors. The specific aims of this proposal are both to explore the surface-mediated changes that occur after transformation, and to further elucidate the structure of the cell membrane and cell surface with particular emphasis on defining factors involved in control of topography of surface recognition sites. Specifically, binding of the lectin Con A to several cAMP sensitive cell lines is being investigated with surface rplicas, freeze-etching and thin sectioning. The modulation of cAMP levels, and concomitant changes in microtubules and microfilaments are beind correlated to lectin binding site distribution. In addition, distribution of negative charges is being mapped on transformed cells, revertant cells and cells infected with temperature-sensitive mutant viruses at both permissive and non-permissive temperatures. The role of calcium and its interaction with the cyclic AMP system is being related to the topography of various binding sites. BIBLIOGRAPHIC REFERENCES: Ryan, G.B., J.Z. Borysenko and M.J. Karnovsky. Factors affecting the redistribution of surface-bound Concanavalin A on human polymorphonuclar leucocytes. J. Cell Biology, 62: 351, 1974.